Techniques for calibrating wireless power transmission systems for operation in multipath wireless power delivery environments

ABSTRACT

The technology described herein relates to techniques for calibrating wireless power transmission systems for operation in multipath wireless power delivery environments. In an implementation, a method of calibrating a wireless power transmission system for operation in a multipath environment is disclosed. The method includes characterizing a receive path from a calibration antennae element to a first antennae element of a plurality of antennae elements of the wireless power transmission system, characterizing a transmit path from the first antennae element to the calibration antennae element, and comparing the transmit path to the receive path to determine a calibration value for the first antennae element in the multipath environment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation U.S. patent application Ser. No.17/244,952, filed Apr. 30, 2021, and issued as U.S. Pat. No. 11,527,916on Dec. 13, 2022; which is a divisional of U.S. patent application Ser.No. 15/596,661, filed May 16, 2017, and issued as U.S. Pat. No.11,038,379 on Jun. 15, 2021; which claims priority to and benefit fromU.S. Provisional Patent Application No. 62/337,147, filed on May 16,2016; each of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The technology described herein relates generally to the field ofwireless power transmission and, more specifically, to techniques forcalibrating wireless power transmission systems in wireless powerdelivery environments.

BACKGROUND

Many electronic devices are powered by batteries. Rechargeable batteriesare often used to avoid the cost of replacing conventional dry-cellbatteries and to conserve precious resources. However, rechargingbatteries with conventional rechargeable battery chargers requiresaccess to an alternating current (AC) power outlet, which is sometimesnot available or not convenient. It is, therefore, desirable to derivepower for electronics wirelessly.

Accordingly, a need exists for technology that overcomes the problemdemonstrated above, as well as one that provides additional benefits.The examples provided herein of some prior or related systems and theirassociated limitations are intended to be illustrative and notexclusive. Other limitations of existing or prior systems will becomeapparent to those of skill in the art upon reading the followingDetailed Description.

SUMMARY

Examples discussed herein relate to techniques for calibrating wirelesspower transmission systems (without an antenna in the far field) foroperation in multipath wireless power delivery environments. In animplementation, a method of calibrating a wireless power transmissionsystem for operation in a multipath environment is disclosed. The methodincludes characterizing a receive path from a calibration antennaeelement to a first antennae element of a plurality of antennae elementsof the wireless power transmission system, characterizing a transmitpath from the first antennae element to the calibration antennaeelement, and comparing the transmit path to the receive path todetermine a calibration value for the first antennae element in themultipath environment.

This Overview is provided to introduce a selection of concepts in asimplified form that are further described below in the TechnicalDisclosure. It may be understood that this Overview is not intended toidentify key features or essential features of the claimed subjectmatter, nor is it intended to be used to limit the scope of the claimedsubject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention are illustrated by wayof example and not limitation in the figures of the accompanyingdrawings, in which like references indicate similar elements.

FIG. 1 depicts a block diagram including an example wireless powerdelivery environment illustrating wireless power delivery from one ormore wireless power transmission systems to various wireless deviceswithin the wireless power delivery environment in accordance with someembodiments.

FIG. 2 depicts a sequence diagram illustrating example operationsbetween a wireless power transmission system and a wireless receiverclient for commencing wireless power delivery in accordance with someembodiments.

FIG. 3 depicts a block diagram illustrating example components of awireless power transmission system in accordance with some embodiments.

FIG. 4 depicts a block diagram illustrating example components of awireless power receiver client in accordance with some embodiments.

FIGS. 5A and 5B depict diagrams illustrating an example multipathwireless power delivery environment in accordance with some embodiments.

FIG. 6 depicts a sequence diagram illustrating an example technique forcalibrating a wireless power transmission system in a multipath wirelesspower delivery environment, according to some embodiments.

FIGS. 7A, 7B and 7C depict a system illustrating example technique forcalibrating a wireless power transmission system in a multipath wirelesspower delivery environment, according to some embodiments.

FIGS. 8A and 8B illustrate an example of uncalibrated system and acalibrated system, respectively, according to some embodiments.

FIG. 9 illustrates an example wireless power transmission system wherethe coupling across the feed lines to the antennas functions as acalibration antenna element (AE) within the enclosure of the wirelesspower transmission system (i.e., internal to the system—integratedcalibration), according to some embodiments.

FIG. 10 depicts a block diagram illustrating example components of arepresentative mobile device or tablet computer with one or morewireless power receiver clients in the form of a mobile (or smart) phoneor tablet computer device in accordance with some embodiments.

FIG. 11 depicts a diagrammatic representation of a machine, in theexample form, of a computer system within which a set of instructions,for causing the machine to perform any one or more of the methodologiesdiscussed herein, may be executed.

DETAILED DESCRIPTION

Techniques are described herein for calibrating wireless powertransmission systems for operation in multipath wireless power deliveryenvironments. Wireless power transmission can occur when multipleantennas of a wireless power transmission system focus energy overmultiple paths to constructively interfere at a particular wirelesspower receiver (or client).

The following description and drawings are illustrative and are not tobe construed as limiting. Numerous specific details are described toprovide a thorough understanding of the disclosure. However, in certaininstances, well-known or conventional details are not described in orderto avoid obscuring the description. References to one or an embodimentin the present disclosure can be, but not necessarily are, references tothe same embodiment; and, such references mean at least one of theembodiments.

Reference in this specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the disclosure. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but no other embodiments.

The terms used in this specification generally have their ordinarymeanings in the art, within the context of the disclosure, and in thespecific context where each term is used. Certain terms that are used todescribe the disclosure are discussed below, or elsewhere in thespecification, to provide additional guidance to the practitionerregarding the description of the disclosure. For convenience, certainterms may be highlighted, for example using italics and/or quotationmarks. The use of highlighting has no influence on the scope and meaningof a term; the scope and meaning of a term is the same, in the samecontext, whether or not it is highlighted. It will be appreciated thatsame thing can be said in more than one way.

Consequently, alternative language and synonyms may be used for any oneor more of the terms discussed herein, nor is any special significanceto be placed upon whether or not a term is elaborated or discussedherein. Synonyms for certain terms are provided. A recital of one ormore synonyms does not exclude the use of other synonyms. The use ofexamples anywhere in this specification, including examples of any termsdiscussed herein, is illustrative only, and is not intended to furtherlimit the scope and meaning of the disclosure or of any exemplifiedterm. Likewise, the disclosure is not limited to various embodimentsgiven in this specification.

Without intent to further limit the scope of the disclosure, examples ofinstruments, apparatus, methods and their related results according tothe embodiments of the present disclosure are given below. Note thattitles or subtitles may be used in the examples for convenience of areader, which in no way should limit the scope of the disclosure. Unlessotherwise defined, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which this disclosure pertains. In the case of conflict, thepresent document, including definitions, will control.

Any headings provided herein are for convenience only and do notnecessarily affect the scope or meaning of the claimed invention.

I. Wireless Power Transmission System Overview/Architecture

FIG. 1 depicts a block diagram including an example wireless powerdelivery environment 100 illustrating wireless power delivery from oneor more wireless power transmission systems (WPTS) 101 a-n (alsoreferred to as “wireless power delivery systems”, “antenna arraysystems” and “wireless chargers”) to various wireless devices 102 a-nwithin the wireless power delivery environment 100, according to someembodiments. More specifically, FIG. 1 illustrates an example wirelesspower delivery environment 100 in which wireless power and/or data canbe delivered to available wireless devices 102 a-102 n having one ormore wireless power receiver clients 103 a-103 n (also referred toherein as “clients” and “wireless power receivers”). The wireless powerreceiver clients are configured to receive and process wireless powerfrom one or more wireless power transmission systems 101 a-101 n.Components of an example wireless power receiver client 103 are shownand discussed in greater detail with reference to FIG. 4 .

As shown in the example of FIG. 1 , the wireless devices 102 a-102 ninclude mobile phone devices and a wireless game controller. However,the wireless devices 102 a-102 n can be any device or system that needspower and is capable of receiving wireless power via one or moreintegrated wireless power receiver clients 103 a-103 n. As discussedherein, the one or more integrated wireless power receiver clientsreceive and process power from one or more wireless power transmissionsystems 101 a-101 n and provide the power to the wireless devices 102a-102 n (or internal batteries of the wireless devices) for operationthereof.

Each wireless power transmission system 101 can include multipleantennas 104 a-n, e.g., an antenna array including hundreds or thousandsof antennas, which are capable of delivering wireless power to wirelessdevices 102 a-102 n. In some embodiments, the antennas areadaptively-phased RF antennas. The wireless power transmission system101 is capable of determining the appropriate phases with which todeliver a coherent power transmission signal to the wireless powerreceiver clients 103 a-103 n. The array is configured to emit a signal(e.g., continuous wave or pulsed power transmission signal) frommultiple antennas at a specific phase relative to each other. It isappreciated that use of the term “array” does not necessarily limit theantenna array to any specific array structure. That is, the antennaarray does not need to be structured in a specific “array” form orgeometry. Furthermore, as used herein the term “array” or “array system”may include related and peripheral circuitry for signal generation,reception and transmission, such as radios, digital logic and modems. Insome embodiments, the wireless power transmission system 101 can have anembedded Wi-Fi hub for data communications via one or more antennas ortransceivers.

The wireless devices 102 can include one or more wireless power receiverclients 103. As illustrated in the example of FIG. 1 , power deliveryantennas 104 a-104 n are shown. The power delivery antennas 104 a areconfigured to provide delivery of wireless radio frequency power in thewireless power delivery environment. In some embodiments, one or more ofthe power delivery antennas 104 a-104 n can alternatively oradditionally be configured for data communications in addition to or inlieu of wireless power delivery. The one or more data communicationantennas are configured to send data communications to and receive datacommunications from the wireless power receiver clients 103 a-103 nand/or the wireless devices 102 a-102 n. In some embodiments, the datacommunication antennas can communicate via Bluetooth™, Wi-Fi™, ZigBee™,etc. Other data communication protocols are also possible.

Each wireless power receiver client 103 a-103 n includes one or moreantennas (not shown) for receiving signals from the wireless powertransmission systems 101 a-101 n. Likewise, each wireless powertransmission system 101 a-101 n includes an antenna array having one ormore antennas and/or sets of antennas capable of emitting continuouswave or discrete (pulse) signals at specific phases relative to eachother. As discussed above, each the wireless power transmission systems101 a-101 n is capable of determining the appropriate phases fordelivering the coherent signals to the wireless power receiver clients102 a-102 n. For example, in some embodiments, coherent signals can bedetermined by computing the complex conjugate of a received beacon (orcalibration) signal at each antenna of the array such that the coherentsignal is phased for delivering power to the particular wireless powerreceiver client that transmitted the beacon (or calibration) signal.

Although not illustrated, each component of the environment, e.g.,wireless device, wireless power transmission system, etc., can includecontrol and synchronization mechanisms, e.g., a data communicationsynchronization module. The wireless power transmission systems 101a-101 n can be connected to a power source such as, for example, a poweroutlet or source connecting the wireless power transmission systems to astandard or primary AC power supply in a building. Alternatively, oradditionally, one or more of the wireless power transmission systems 101a-101 n can be powered by a battery or via other mechanisms, e.g., solarcells, etc.

The wireless power receiver clients 102 a-102 n and/or the wirelesspower transmission systems 101 a-101 n are configured to operate in amultipath wireless power delivery environment. That is, the wirelesspower receiver clients 102 a-102 n and the wireless power transmissionsystems 101 a-101 n are configured to utilize reflective objects 106such as, for example, walls or other RF reflective obstructions withinrange to transmit beacon (or calibration) signals and/or receivewireless power and/or data within the wireless power deliveryenvironment. The reflective objects 106 can be utilized formulti-directional signal communication regardless of whether a blockingobject is in the line of sight between the wireless power transmissionsystem and the wireless power receiver clients 103 a-103 n.

As described herein, each wireless device 102 a-102 n can be any systemand/or device, and/or any combination of devices/systems that canestablish a connection with another device, a server and/or othersystems within the example environment 100. In some embodiments, thewireless devices 102 a-102 n include displays or other outputfunctionalities to present data to a user and/or input functionalitiesto receive data from the user. By way of example, a wireless device 102can be, but is not limited to, a video game controller, a serverdesktop, a desktop computer, a computer cluster, a mobile computingdevice such as a notebook, a laptop computer, a handheld computer, amobile phone, a smart phone, a PDA, a Blackberry device, a Treo, and/oran iPhone, etc. By way of example and not limitation, the wirelessdevice 102 can also be any wearable device such as watches, necklaces,rings or even devices embedded on or within the customer. Other examplesof a wireless device 102 include, but are not limited to, safety sensors(e.g., fire or carbon monoxide), electric toothbrushes, electronic doorlock/handles, electric light switch controller, electric shavers, etc.

Although not illustrated in the example of FIG. 1 , the wireless powertransmission system 101 and the wireless power receiver clients 103a-103 n can each include a data communication module for communicationvia a data channel. Alternatively, or additionally, the wireless powerreceiver clients 103 a-103 n can direct the wireless devices 102 a-102 nto communicate with the wireless power transmission system via existingdata communications modules. In some embodiments the beacon signal,which is primarily referred to herein as a continuous waveform, canalternatively or additionally take the form of a modulated signal.

FIG. 2 depicts a sequence diagram 200 illustrating example operationsbetween a wireless power delivery system (e.g., WPTS 101) and a wirelesspower receiver client (e.g., wireless power receiver client 103) forestablishing wireless power delivery in a multipath wireless powerdelivery, according to an embodiment. Initially, communication isestablished between the wireless power transmission system 101 and thepower receiver client 103. The initial communication can be, forexample, a data communication link that is established via one or moreantennas 104 of the wireless power transmission system 101. Asdiscussed, in some embodiments, one or more of the antennas 104 a-104 ncan be data antennas, wireless power transmission antennas, ordual-purpose data/power antennas. Various information can be exchangedbetween the wireless power transmission system 101 and the wirelesspower receiver client 103 over this data communication channel. Forexample, wireless power signaling can be time sliced among variousclients in a wireless power delivery environment. In such cases, thewireless power transmission system 101 can send beacon scheduleinformation, e.g., Beacon Beat Schedule (BBS) cycle, power cycleinformation, etc., so that the wireless power receiver client 103 knowswhen to transmit (broadcast) its beacon signals and when to listen forpower, etc.

Continuing with the example of FIG. 2 , the wireless power transmissionsystem 101 selects one or more wireless power receiver clients forreceiving power and sends the beacon schedule information to the selectwireless power receiver clients 103. The wireless power transmissionsystem 101 can also send power transmission scheduling information sothat the wireless power receiver client 103 knows when to expect (e.g.,a window of time) wireless power from the wireless power transmissionsystem. The wireless power receiver client 103 then generates a beacon(or calibration) signal and broadcasts the beacon during an assignedbeacon transmission window (or time slice) indicated by the beaconschedule information, e.g., BBS cycle. As discussed herein, the wirelesspower receiver client 103 includes one or more antennas (ortransceivers) which have a radiation and reception pattern inthree-dimensional space proximate to the wireless device 102 in whichthe wireless power receiver client 103 is embedded.

The wireless power transmission system 101 receives the beacon from thepower receiver client 103 and detects and/or otherwise measures thephase (or direction) from which the beacon signal is received atmultiple antennas. The wireless power transmission system 101 thendelivers wireless power to the power receiver client 103 from themultiple antennas 103 based on the detected or measured phase (ordirection) of the received beacon at each of the corresponding antennas.In some embodiments, the wireless power transmission system 101determines the complex conjugate of the measured phase of the beacon anduses the complex conjugate to determine a transmit phase that configuresthe antennas for delivering and/or otherwise directing wireless power tothe wireless power receiver client 103 via the same path over which thebeacon signal was received from the wireless power receiver client 103.

In some embodiments, the wireless power transmission system 101 includesmany antennas. One or more of the many antennas may be used to deliverpower to the power receiver client 103. The wireless power transmissionsystem 101 can detect and/or otherwise determine or measure phases atwhich the beacon signals are received at each antenna. The large numberof antennas may result in different phases of the beacon signal beingreceived at each antenna of the wireless power transmission system 101.As discussed above, the wireless power transmission system 101 candetermine the complex conjugate of the beacon signals received at eachantenna. Using the complex conjugates, one or more antennas may emit asignal that takes into account the effects of the large number ofantennas in the wireless power transmission system 101. In other words,the wireless power transmission system 101 can emit a wireless powertransmission signal from the one or more antennas in such a way as tocreate an aggregate signal from the one or more of the antennas thatapproximately recreates the waveform of the beacon in the oppositedirection. Said another way, the wireless power transmission system 101can deliver wireless RF power to the wireless power receiver clients viathe same paths over which the beacon signal is received at the wirelesspower transmission system 101. These paths can utilize reflectiveobjects 106 within the environment. Additionally, the wireless powertransmission signals can be simultaneously transmitted from the wirelesspower transmission system 101 such that the wireless power transmissionsignals collectively match the antenna radiation and reception patternof the client device in a three-dimensional (3D) space proximate to theclient device.

As shown, the beacon (or calibration) signals can be periodicallytransmitted by wireless power receiver clients 103 within the powerdelivery environment according to, for example, the BBS, so that thewireless power transmission system 101 can maintain knowledge and/orotherwise track the location of the power receiver clients 103 in thewireless power delivery environment. The process of receiving beaconsignals from a wireless power receiver client 103 at the wireless powertransmission system and, in turn, responding with wireless powerdirected to that particular wireless power receiver client is referredto herein as retrodirective wireless power delivery.

Furthermore, as discussed herein, wireless power can be delivered inpower cycles defined by power schedule information. A more detailedexample of the signaling required to commence wireless power delivery isdescribed now with reference to FIG. 3 .

FIG. 3 depicts a block diagram illustrating example components of awireless power transmission system 300, in accordance with anembodiment. As illustrated in the example of FIG. 3 , the wirelesscharger 300 includes a master bus controller (MBC) board and multiplemezzanine boards that collectively comprise the antenna array. The MBCincludes control logic 310, an external data interface (I/F) 315, anexternal power interface (I/F) 320, a communication block 330 and proxy340. The mezzanine (or antenna array boards 350) each include multipleantennas 360 a-360 n. Some or all of the components can be omitted insome embodiments. Additional components are also possible. For example,in some embodiments only one of communication block 330 or proxy 340 maybe included.

The control logic 310 is configured to provide control and intelligenceto the array components. The control logic 310 may comprise one or moreprocessors, FPGAs, memory units, etc., and direct and control thevarious data and power communications. The communication block 330 candirect data communications on a data carrier frequency, such as the basesignal clock for clock synchronization. The data communications can beBluetooth™, Wi-Fi™, ZigBee™, etc., including combinations or variationsthereof. Likewise, the proxy 340 can communicate with clients via datacommunications as discussed herein. The data communications can be, byway of example and not limitation, Bluetooth™, Wi-Fi™, ZigBee™, etc.Other communication protocols are possible.

In some embodiments, the control logic 310 can also facilitate and/orotherwise enable data aggregation for Internet of Things (IoT) devices.In some embodiments, wireless power receiver clients can access, trackand/or otherwise obtain IoT information about the device in which thewireless power receiver client is embedded and provide that IoTinformation to the wireless power transmission system 300 over a dataconnection. This IoT information can be provided to via an external datainterface 315 to a central or cloud-based system (not shown) where thedata can be aggregated, processed, etc. For example, the central systemcan process the data to identify various trends across geographies,wireless power transmission systems, environments, devices, etc. In someembodiments, the aggregated data and or the trend data can be used toimprove operation of the devices via remote updates, etc. Alternatively,or additionally, in some embodiments, the aggregated data can beprovided to third party data consumers. In this manner, the wirelesspower transmission system acts as a Gateway or Enabler for the IoTs. Byway of example and not limitation, the IoT information can includecapabilities of the device in which the wireless power receiver clientis embedded, usage information of the device, power levels of thedevice, information obtained by the device or the wireless powerreceiver client itself, e.g., via sensors, etc.

The external power interface 320 is configured to receive external powerand provide the power to various components. In some embodiments, theexternal power interface 320 may be configured to receive a standardexternal 24 Volt power supply. In other embodiments, the external powerinterface 320 can be, for example, 120/240 Volt AC mains to an embeddedDC power supply which sources the required 12/24/48 Volt DC to providethe power to various components. Alternatively, the external powerinterface could be a DC supply which sources the required 12/24/48 VoltsDC. Alternative configurations are also possible.

In operation, the MBC, which controls the wireless power transmissionsystem 300, receives power from a power source and is activated. The MBCthen activates the proxy antenna elements on the wireless powertransmission system and the proxy antenna elements enter a default“discovery” mode to identify available wireless receiver clients withinrange of the wireless power transmission system. When a client is found,the antenna elements on the wireless power transmission system power on,enumerate, and (optionally) calibrate.

The MBC then generates beacon transmission scheduling information andpower transmission scheduling information during a scheduling process.The scheduling process includes selection of power receiver clients. Forexample, the MBC can select power receiver clients for powertransmission and generate a BBS cycle and a Power Schedule (PS) for theselected wireless power receiver clients. As discussed herein, the powerreceiver clients can be selected based on their corresponding propertiesand/or requirements.

In some embodiments, the MBC can also identify and/or otherwise selectavailable clients that will have their status queried in the ClientQuery Table (CQT). Clients that are placed in the CQT are those on“standby”, e.g., not receiving a charge. The BBS and PS are calculatedbased on vital information about the clients such as, for example,battery status, current activity/usage, how much longer the client hasuntil it runs out of power, priority in terms of usage, etc.

The Proxy Antenna Element (AE) broadcasts the BBS to all clients. Asdiscussed herein, the BBS indicates when each client should send abeacon. Likewise, the PS indicates when and to which clients the arrayshould send power to and when clients should listen for wireless power.Each client starts broadcasting its beacon and receiving power from thearray per the BBS and PS. The Proxy AE can concurrently query the ClientQuery Table to check the status of other available clients. In someembodiments, a client can only exist in the BBS or the CQT (e.g.,waitlist), but not in both. The information collected in the previousstep continuously and/or periodically updates the BBS cycle and/or thePS.

FIG. 4 is a block diagram illustrating example components of a wirelesspower receiver client 400, in accordance with some embodiments. Asillustrated in the example of FIG. 4 , the receiver 400 includes controllogic 410, battery 420, an IoT control module 425, communication block430 and associated antenna 470, power meter 440, rectifier 450, acombiner 455, beacon signal generator 460, beacon coding unit 462 and anassociated antenna 480, and switch 465 connecting the rectifier 450 orthe beacon signal generator 460 to one or more associated antennas 490a-n. Some or all of the components can be omitted in some embodiments.For example, in some embodiments, the wireless power receiver client 400does not include its own antennas but instead utilizes and/or otherwiseshares one or more antennas (e.g., Wi-Fi antenna) of the wireless devicein which the wireless power receiver client is embedded. Moreover, insome embodiments, the wireless power receiver client may include asingle antenna that provides data transmission functionality as well aspower/data reception functionality. Additional components are alsopossible.

A combiner 455 receives and combines the received power transmissionsignals from the power transmitter in the event that the receiver 400has more than one antenna. The combiner can be any combiner or dividercircuit that is configured to achieve isolation between the output portswhile maintaining a matched condition. For example, the combiner 455 canbe a Wilkinson Power Divider circuit. The rectifier 450 receives thecombined power transmission signal from the combiner 455, if present,which is fed through the power meter 440 to the battery 420 forcharging. In other embodiments, each antenna's power path can have itsown rectifier 450 and the DC power out of the rectifiers is combinedprior to feeding the power meter 440. The power meter 440 can measurethe received power signal strength and provides the control logic 410with this measurement.

Battery 420 can include protection circuitry and/or monitoringfunctions. Additionally, the battery 420 can include one or morefeatures, including, but not limited to, current limiting, temperatureprotection, over/under voltage alerts and protection, and coulombmonitoring.

The control logic 410 receives and processes the battery power levelfrom the battery 420 itself. The control logic 410 may alsotransmit/receive via the communication block 430 a data signal on a datacarrier frequency, such as the base signal clock for clocksynchronization. The beacon signal generator 460 generates the beaconsignal, or calibration signal, transmits the beacon signal using eitherthe antenna 480 or 490 after the beacon signal is encoded.

It may be noted that, although the battery 420 is shown as charged by,and providing power to, the wireless power receiver client 400, thereceiver may also receive its power directly from the rectifier 450.This may be in addition to the rectifier 450 providing charging currentto the battery 420, or in lieu of providing charging. Also, it may benoted that the use of multiple antennas is one example of implementationand the structure may be reduced to one shared antenna.

In some embodiments, the control logic 410 and/or the IoT control module425 can communicate with and/or otherwise derive IoT information fromthe device in which the wireless power receiver client 400 is embedded.Although not shown, in some embodiments, the wireless power receiverclient 400 can have one or more data connections (wired or wireless)with the device in which the wireless power receiver client 400 isembedded over which IoT information can be obtained. Alternatively, oradditionally, IoT information can be determined and/or inferred by thewireless power receiver client 400, e.g., via one or more sensors. Asdiscussed above, the IoT information can include, but is not limited to,information about the capabilities of the device in which the wirelesspower receiver client 400 is embedded, usage information of the devicein which the wireless power receiver client 400 is embedded, powerlevels of the battery or batteries of the device in which the wirelesspower receiver client 400 is embedded, and/or information obtained orinferred by the device in which the wireless power receiver client isembedded or the wireless power receiver client itself, e.g., viasensors, etc.

In some embodiments, a client identifier (ID) module 415 stores a clientID that can uniquely identify the wireless power receiver client 400 ina wireless power delivery environment. For example, the ID can betransmitted to one or more wireless power transmission systems whencommunication is established. In some embodiments, wireless powerreceiver clients may also be able to receive and identify other wirelesspower receiver clients in a wireless power delivery environment based onthe client ID.

An optional motion sensor 495 can detect motion and signal the controllogic 410 to act accordingly. For example, a device receiving power mayintegrate motion detection mechanisms such as accelerometers orequivalent mechanisms to detect motion. Once the device detects that itis in motion, it may be assumed that it is being handled by a user, andwould trigger a signal to the array to either to stop transmittingpower, or to lower the power transmitted to the device. In someembodiments, when a device is used in a moving environment like a car,train or plane, the power might only be transmitted intermittently or ata reduced level unless the device is critically low on power.

FIGS. 5A and 5B depict diagrams illustrating an example multipathwireless power delivery environment 500, according to some embodiments.The multipath wireless power delivery environment 500 includes a useroperating a wireless device 502 including one or more wireless powerreceiver clients 503. The wireless device 502 and the one or morewireless power receiver clients 503 can be wireless device 102 of FIG. 1and wireless power receiver client 103 of FIG. 1 or wireless powerreceiver client 400 of FIG. 4 , respectively, although alternativeconfigurations are possible. Likewise, wireless power transmissionsystem 501 can be wireless power transmission system 101 FIG. 1 orwireless power transmission system 300 of FIG. 3 , although alternativeconfigurations are possible. The multipath wireless power deliveryenvironment 500 includes reflective objects 506 and various absorptiveobjects, e.g., users, or humans, furniture, etc.

Wireless device 502 includes one or more antennas (or transceivers) thathave a radiation and reception pattern 510 in three-dimensional spaceproximate to the wireless device 102. The one or more antennas (ortransceivers) can be wholly or partially included as part of thewireless device 102 and/or the wireless power receiver client (notshown). For example, in some embodiments one or more antennas, e.g.,Wi-Fi, Bluetooth, etc. of the wireless device 502 can be utilized and/orotherwise shared for wireless power reception. As shown in the exampleof FIGS. 5A and 5B, the radiation and reception pattern 510 comprises alobe pattern with a primary lobe and multiple side lobes. Other patternsare also possible.

The wireless device 502 transmits a beacon (or calibration) signal overmultiple paths to the wireless power transmission system 501. Asdiscussed herein, the wireless device 502 transmits the beacon in thedirection of the radiation and reception pattern 510 such that thestrength of the received beacon signal by the wireless powertransmission system, e.g., received signal strength indication (RSSI),depends on the radiation and reception pattern 510. For example, beaconsignals are not transmitted where there are nulls in the radiation andreception pattern 510 and beacon signals are the strongest at the peaksin the radiation and reception pattern 510, e.g., peak of the primarylobe. As shown in the example of FIG. 5A, the wireless device 502transmits beacon signals over five paths P1-P5. Paths P4 and P5 areblocked by reflective and/or absorptive object 506. The wireless powertransmission system 501 receives beacon signals of increasing strengthsvia paths P1-P3. The bolder lines indicate stronger signals. In someembodiments the beacon signals are directionally transmitted in thismanner, for example, to avoid unnecessary RF energy exposure to theuser.

A fundamental property of antennas is that the receiving pattern(sensitivity as a function of direction) of an antenna when used forreceiving is identical to the far-field radiation pattern of the antennawhen used for transmitting. This is a consequence of the reciprocitytheorem in electromagnetism. As shown in the example of FIGS. 5A and 5B,the radiation and reception pattern 510 is a three-dimensional lobeshape. However, the radiation and reception pattern 510 can be anynumber of shapes depending on the type or types, e.g., horn antennas,simple vertical antenna, etc. used in the antenna design. For example,the radiation and reception pattern 510 can comprise various directivepatterns. Any number of different antenna radiation and receptionpatterns are possible for each of multiple client devices in a wirelesspower delivery environment.

Referring again to FIG. 5A, the wireless power transmission system 501receives the beacon (or calibration) signal via multiple paths P1-P3 atmultiple antennas or transceivers. As shown, paths P2 and P3 are directline of sight paths while path P1 is a non-line of sight path. Once thebeacon (or calibration) signal is received by the wireless powertransmission system 501, the power transmission system 501 processes thebeacon (or calibration) signal to determine one or more receivecharacteristics of the beacon signal at each of the multiple antennas.For example, among other operations, the wireless power transmissionsystem 501 can measure the phases at which the beacon signal is receivedat each of the multiple antennas or transceivers.

The wireless power transmission system 501 processes the one or morereceive characteristics of the beacon signal at each of the multipleantennas to determine or measure one or more wireless power transmitcharacteristics for each of the multiple RF transceivers based on theone or more receive characteristics of the beacon (or calibration)signal as measured at the corresponding antenna or transceiver. By wayof example and not limitation, the wireless power transmitcharacteristics can include phase settings for each antenna ortransceiver, transmission power settings, etc.

As discussed herein, the wireless power transmission system 501determines the wireless power transmit characteristics such that, oncethe antennas or transceivers are configured, the multiple antennas ortransceivers are operable to transit a wireless power signal thatmatches the client radiation and reception pattern in thethree-dimensional space proximate to the client device. FIG. 5Billustrates the wireless power transmission system 501 transmittingwireless power via paths P1-P3 to the wireless device 502.Advantageously, as discussed herein, the wireless power signal matchesthe client radiation and reception pattern 510 in the three-dimensionalspace proximate to the client device. Said another way, the wirelesspower transmission system will transmit the wireless power signals inthe direction in which the wireless power receiver has maximum gain,e.g., will receive the most wireless power. As a result, no signals aresent in directions in which the wireless power receiver cannot receivepower, e.g., nulls and blockages. In some embodiments, the wirelesspower transmission system 501 measures the RSSI of the received beaconsignal and if the beacon is less than a threshold value, the wirelesspower transmission system will not send wireless power over that path.

The three paths shown in the example of FIGS. 5A and 5B are illustratedfor simplicity, it is appreciated that any number of paths can beutilized for transmitting power to the wireless device 502 depending on,among other factors, reflective and absorptive objects in the wirelesspower delivery environment.

Although the example of FIG. 5A illustrates transmitting a beacon (orcalibration) signal in the direction of the radiation and receptionpattern 510, it is appreciated that, in some embodiments, beacon signalscan alternatively or additionally be omni-directionally transmitted.

II. WPTS Calibration in Multipath Environment

As discussed above, wireless power transmission systems can wirelesslytransmit power to wireless power receiver clients in a multipathwireless power delivery environment by focusing wireless power signalsover multiple paths to specific areas or regions (also referred to asfocal points) proximate to a wireless power receiver client. In orderfor this operation to be successful, the multiple signals must beappropriately phased such that the signals are additive (orconstructively interfere) at the focal point. The process of adjustingthe phases to ensure that the signals arrive at the receiver in-phase isreferred to herein as calibration.

The calibration process can be performed in a number of ways at varioustimes depending on the design of the wireless power transmission systemand other factors. For example, in some embodiments, the calibrationprocess occurs at system startup to account for ambiguity in the phasesof the multiple antennas (or antennae elements). The calibration can berepeated if, for example, there are significant environmental changes,e.g., in temperature, etc. In some embodiments, the system can bedesigned to startup in the same phase state every time. With thesedesigns, the calibration may only need to occur once, e.g., one-timefactory calibration. However, these systems can be very complex andexpensive.

Accordingly, the typical approach to calibration is to have a clientantenna (e.g., calAE) located in the far field send a signal thatpresents a uniform waveform when it hits an antenna array.Unfortunately, this solution is untenable in a multipath environment fora variety of reasons. First, indoor environments have reflections thatdisrupt or change the uniformity, e.g., phase distribution, of waveformsas they are received at the array. Regardless, a client antennatypically needs to be located in the far field for calibration, which ismuch further away than the client can get from the charger in amultipath environment, e.g., indoor environment.

Techniques are discussed herein for calibrating wireless powertransmission systems for operation in multipath wireless power deliveryenvironments. Importantly, at least one unique aspect of the techniquesdiscussed herein is that they are performed round trip. That is, thetransmit path is characterized, the receive path is characterized, andthen the system identifies differences between the ideal and thedetected paths. Advantageously, by exercising the transmit and thereceive paths, the environmental constraints can be identified andaccounted for so that the client does not need to be located in the farfield.

As discussed above, the wireless power transmission system must becalibrated if there is any ambiguity in the phase. Phase error can beintroduced from a variety of sources. For example, phase error can beinside the detection circuit itself, the RF signal source on eachantenna element, within the traces in the system, and/or based on otherfactors, e.g., environmental factors such as thermal drift, etc.Additional sources of phase error can include: MBC Clock Skew inDistribution, MBC Clock Buffer Temperature Drift, Warm-up Time andRecalibration errors/drift, Clock Distribution Path Length Differences(Cabled solution), and PLL Start-up Phase inconsistencies. Potentiallyother unidentified sources of error as well. The techniques discussedherein are a ‘catch-all’ providing a single correction for the sum ofall errors. More specifically, the techniques discussed herein accountfor any and all ambiguity in the phase so that all antennas are alignedto a common reference.

Definitions and components discussed herein:

-   -   Calibration AE (CalAE): Modified AE design that behaves as a        mock client. Capable of sending a Beacon (or calibration) signal        and detecting RF energy received at its antenna. Positioned        external to main array structure.    -   Reference AE/Antenna (RefAE): A single antenna is selected from        the array to provide a common reference. All other AE Antennas        are aligned to this Reference.    -   All other AE/Ant (DUT): All other Antenna are calibrated one at        a time against the Reference AE.

FIG. 6 depicts a sequence diagram illustrating an example technique forcalibrating a wireless power transmission system in a multipath wirelesspower delivery environment, according to some embodiments. Thecalibration technique discussed with reference to FIG. 6 takes intoaccount each source of error to align the RF output to a zero-degreereference. The technique includes two processes: (1) static tune; and(2) beacon tune. The order in which the processes are performed is notimportant. The calibration value is the difference between the valuesderived by each process.

To begin, (at step 1) the CalAE Beacons, the RefAE and DUT detect thephase. The detected phases are saved to MBC. Next, (at step 2) the MBCcommands RefAE to continuously transmit Detected Phase. The MBC (at step3) commands DUT to transmit signals in sequential phase settings [0, 22,. . . , 337]. The CalAE, (at step 4), collects data on received power[Prx0, Prx22, . . . , Prx337] for MBC. The MBC, (at step 5), determinesoptimum phase transmitted from DUT by peak power received by the CalAE,i.e., Optimum Phase=Pmax([Prx0, Prx22, . . . , Prx337]). The MBC, (atstep 6), calculates the calibration value for DUT as difference betweenDetected Phase and Optimum Phase.

Steps 1-6 repeated for each antenna element (AE)/Antenna in the array.The calibration value is added to all detected phases during normaloperation.

FIGS. 7A-7C depict a system illustrating an example technique forcalibrating a wireless power transmission system in a multipath wirelesspower delivery environment, according to some embodiments. Thecalibration technique discussed with reference to FIGS. 7A-7C takes intoaccount multiple sources of error to align all antenna elements at theRF output to a zero-degree reference. Like FIG. 6 , the techniqueincludes two processes: (1) static tune; and (2) beacon tune. The orderin which the processes are performed is not important. The calibrationvalue is the difference between the values derived by each process.

Referring first to FIG. 7A, FIG. 7A illustrates a beacon from thecalibration antenna (labeled CalAE). As shown, there is a vector drawingfor a phase delay along each path and the individual phase references(essentially the total phase shift through that element). The systemaligns to the phi ref 1, channel 1, antenna 1 as shown. Antenna 1 andantenna 2 are detecting and have different internal phase references sothey detect different phases from the beacon signal relative to oneanother. FIG. 7B illustrates values that the antennas detect. The valuesare measured phases plus the phase received.

FIG. 7C shows the next step where the reference antenna (antenna 1)sends back what it detected and the other antenna (antenna 2) sends backa signal with sequential phase settings 0-337. It should be noted thatmore or fewer phase settings are possible. The calAE records the peakpower as shown. Additionally, the calculation of phase is shown.

FIG. 7C also illustrates an attempt to correlate the detected phase,what should be transmitted for the peak amplitude and what the systemknows is the correct value. All values are fed back to the master buscontroller (e.g., central controller) which controls the calibrationprocess, the calAE and the test antennas (DUT). As shown in the exampleof FIG. 7C, a rough calculation of the peak value minus the detectedvalue for the phase is shown as well as an example of how the equationis resolved.

FIGS. 8A and 8B illustrate an example uncalibrated system and an examplecalibrated system, respectively, according to some embodiments. Thesignals shown in FIG. 8A are out of phase and, thus, do not provide forthe ability to transmit power because the signals do not constructivelyinterfere at a power receiver client (shown as calAE in the example ofFIGS. 8A and 8B). In FIG. 8A, without calibration, the multiple antennasof the WPTS transmit the complex conjugate back over the same phase pathfrom which the beacon signal is received (see phi ref 1 and phi ref 2arriving at the calAE). Depending on phi ref 1 and phi ref 2, a clientwould likely receive different levels of power (or possibly no power atall) as the signals are likely out of phase.

In FIG. 8B the power is transmitted after adding in the calculatedcalibration value so that the signals constructively interfere (generatea focused signal) for power reception by a receiver client. Morespecifically, the cal value is added in so that both signals align tothe same phase at the calAE (or client). As discussed herein, withoutcalibration, it is possible (if not likely) that zero power istransferred to a client because the signals are not unaligned and, thus,not focused. As discussed herein, the system is based on additiveconstructive interference of many in phase signals all hitting the samepoint at the same time to constructively interfere. When the system isnot calibrated, a combination of constructive and destructiveinterference occurs which can lead to significant power loss (randomnoise) or no power transfer to the client.

Integrated Calibration

To this point, a dedicated external calibration module (CalAE) has beendiscussed. FIG. 9 illustrates an example wireless power transmissionsystem where the coupling across the feed lines to the antennasfunctions as a calibration AE within the enclosure of the wireless powertransmission system (i.e., internal to the system—integratedcalibration). The internal coupling can utilize the same algorithmdiscussed herein (e.g., with reference to FIG. 6 ) to accomplish thecalibration.

In the example of FIG. 9 , the cylindrical shape of the wireless powertransmission system allows for the coupling across the feed lines to theantennas. The only limitation of the internal calAE is that it has to be“heard” and “hear” all of the other antennas. The internal calAE is ableto couple energy in and out of all of the other antennas. Whether theCalAE does that through antennas over the air or through internalcoupling is not important to the calibration technique or algorithm aslong as the internal CalAE uses a consistent path and can detect andoutput a signal that can be detected by all of the other antennas.

Factory Calibration

The embodiments above are primarily discussed with reference to run-timecalibration, e.g., have to calibrate each time startup. However, in someembodiments, calibration can also be performed at manufacturing time.For example, the system can attempt to account for any phase differencesso that it starts up in the same phase state every time, e.g., withfixed path lengths. Unfortunately, fixed paths lengths can be difficultto achieve, costly and wasteful.

Another way one-time factory calibration can be achieved is bydetermining the path-length differences (and all other potential phasedifferences) once, and store these values in calibration registers thatadjust the system automatically each time the system is started up.Thus, no calibration needs to be performed at startup. For example, thedesign can match clock lengths and signal traces on the hardware throughthe whole system. However, this can lead to more complex designsresulting a more intricate PCBs, etc., For example, if the longest tracehas to be 12 inches, the rest of traces have to also be 12 inches, evenif the closest Antenna Matrix Board (AMB) is only two inches away whichwill force the designer to find an extra 10 inches of run on the PCB tomatch the length of all signals. By pushing some of the complexity intocalibration, the techniques described herein facilitate a more relaxeddesign.

The calibration values can be determined during a manufacturing time.Other variables could also be taken into account using this method. Forexample, any phase variability constraints such as environment, thermaland other design characteristics that are not accounted for during thedesign phase can be fixed through calibration. For example,manufacturing time calibration can occur in a controlled environment atvarious temperatures to account for thermal drift. The values can bestored in registers and the wireless power transmission system candynamically adjust the values (either at startup, periodically, orcontinuously) based on the current environmental conditions. Otherregister values can also be estimated and stored. The values can beadjusted over the life of the part, etc. While the various designsdiscussed here only require a single calibration at manufacturing time,the designs tend to be more complex as many variables need to beaccounted for and values stored in registers for on-the-fly adjustments.

IV. Additional Calibration Examples

In addition to some of the information discussed herein, variousapproaches to calibration including conventional one-way approaches aredescribed in greater detail below. More specifically, plane wave andknown excitations are discussed. For example, when a plane wave isexcited, the calibration antenna must be sufficiently far away from theantenna array so that the array collectively appears as a single pointsource. It should be noted that plane wave excitation describing thephase distribution across all the antennas should be zero degreesbecause the wave is uniform. With such known wave excitations, it maynot all be zero degrees but it is a known distribution, and should bethe same every time.

For example, if one knew the phase distributions between antennas, adetermination could be made as to where the system was focused (30degrees from antenna 1, 0 degrees from antenna 2, etc.) e.g., at 20 cmdirectly in front of the system one would have a focused illumination.This is an example of a known wave distribution. One problem with thisdesign is that for such calibration technique to work, it needs to beperformed in an open field since reflections from actual obstacles inrealistic setups (i.e., an office) would have an impact on the collectedinformation. Also, this process does not account for thetransmitter-side anomalies which may have a different phase error thatthe receive-side.

In-circuit calibration is related to internal coupling and involves adifferent algorithm. With this technique, external CalAE is removed andcell-to-cell calibration is performed. In cell-to-cell calibration,everything is referenced to antenna 0. With this approach, antenna 1 iscalibrated, where the calibration values are stored relative to antenna0. Antennas 1 and 2 go through the same routine which implicitly haveantenna 2 being in phase with respect to antenna 0. This is more of abasic approach where the calibrating antennas are in close proximity toeach other and coupling is assured (i.e., the antennas could hear eachother constantly). Another approach that could be useful if, forexample, the configuration of the charger does not provide sufficientcoupling from any antenna to any other antenna. This technique can beused either on an antenna to antenna basis or group of antennas to groupof antennas (have AMBs—antenna matrix boards phases).

In another embodiment, a super runtime feedback loop is implemented. Forexample, an antenna would know that it is supposed to output 14 degreesof phase difference, and continuously monitors itself and adjusts itsphase, which helps to eliminate the need for calibration.

III. Example Systems

FIG. 10 depicts a block diagram illustrating example components of arepresentative mobile device or tablet computer 1000 with a wirelesspower receiver or client in the form of a mobile (or smart) phone ortablet computer device, according to an embodiment. Various interfacesand modules are shown with reference to FIG. 10 , however, the mobiledevice or tablet computer does not require all of modules or functionsfor performing the functionality described herein. It is appreciatedthat, in many embodiments, various components are not included and/ornecessary for operation of the category controller. For example,components such as GPS radios, cellular radios, and accelerometers maynot be included in the controllers to reduce costs and/or complexity.Additionally, components such as ZigBee radios and RFID transceivers,along with antennas, can populate the Printed Circuit Board.

The wireless power receiver client can be a power receiver client 103 ofFIG. 1 , although alternative configurations are possible. Additionally,the wireless power receiver client can include one or more RF antennasfor reception of power and/or data signals from a power transmissionsystem, e.g., wireless power transmission system 101 of FIG. 1 .

FIG. 11 depicts a diagrammatic representation of a machine, in theexample form, of a computer system within which a set of instructions,for causing the machine to perform any one or more of the methodologiesdiscussed herein, may be executed.

In the example of FIG. 11 , the computer system includes a processor,memory, non-volatile memory, and an interface device. Various commoncomponents (e.g., cache memory) are omitted for illustrative simplicity.The computer system 1100 is intended to illustrate a hardware device onwhich any of the components depicted in the example of FIG. 1 (and anyother components described in this specification) can be implemented.For example, the computer system can be any radiating object or antennaarray system. The computer system can be of any applicable known orconvenient type. The components of the computer system can be coupledtogether via a bus or through some other known or convenient device.

The processor may be, for example, a conventional microprocessor such asan Intel Pentium microprocessor or Motorola power PC microprocessor. Oneof skill in the relevant art will recognize that the terms“machine-readable (storage) medium” or “computer-readable (storage)medium” include any type of device that is accessible by the processor.

The memory is coupled to the processor by, for example, a bus. Thememory can include, by way of example but not limitation, random accessmemory (RAM), such as dynamic RAM (DRAM) and static RAM (SRAM). Thememory can be local, remote, or distributed.

The bus also couples the processor to the non-volatile memory and driveunit. The non-volatile memory is often a magnetic floppy or hard disk, amagnetic-optical disk, an optical disk, a read-only memory (ROM), suchas a CD-ROM, EPROM, or EEPROM, a magnetic or optical card, or anotherform of storage for large amounts of data. Some of this data is oftenwritten, by a direct memory access process, into memory during executionof software in the computer 1300. The non-volatile storage can be local,remote, or distributed. The non-volatile memory is optional becausesystems can be created with all applicable data available in memory. Atypical computer system will usually include at least a processor,memory, and a device (e.g., a bus) coupling the memory to the processor.

Software is typically stored in the non-volatile memory and/or the driveunit. Indeed, for large programs, it may not even be possible to storethe entire program in the memory. Nevertheless, it should be understoodthat for software to run, if necessary, it is moved to a computerreadable location appropriate for processing, and for illustrativepurposes, that location is referred to as the memory in this paper. Evenwhen software is moved to the memory for execution, the processor willtypically make use of hardware registers to store values associated withthe software, and local cache that, ideally, serves to speed upexecution. As used herein, a software program is assumed to be stored atany known or convenient location (from non-volatile storage to hardwareregisters) when the software program is referred to as “implemented in acomputer-readable medium”. A processor is considered to be “configuredto execute a program” when at least one value associated with theprogram is stored in a register readable by the processor.

The bus also couples the processor to the network interface device. Theinterface can include one or more of a modem or network interface. Itwill be appreciated that a modem or network interface can be consideredto be part of the computer system. The interface can include an analogmodem, isdn modem, cable modem, token ring interface, satellitetransmission interface (e.g. “direct PC”), or other interfaces forcoupling a computer system to other computer systems. The interface caninclude one or more input and/or output devices. The I/O devices caninclude, by way of example but not limitation, a keyboard, a mouse orother pointing device, disk drives, printers, a scanner, and other inputand/or output devices, including a display device. The display devicecan include, by way of example but not limitation, a cathode ray tube(CRT), liquid crystal display (LCD), or some other applicable known orconvenient display device. For simplicity, it is assumed thatcontrollers of any devices not depicted in the example of FIG. 9 residein the interface.

In operation, the computer system 1100 can be controlled by operatingsystem software that includes a file management system, such as a diskoperating system. One example of operating system software withassociated file management system software is the family of operatingsystems known as Windows® from Microsoft Corporation of Redmond,Washington, and their associated file management systems. Anotherexample of operating system software with its associated file managementsystem software is the Linux operating system and its associated filemanagement system. The file management system is typically stored in thenon-volatile memory and/or drive unit and causes the processor toexecute the various acts required by the operating system to input andoutput data and to store data in the memory, including storing files onthe non-volatile memory and/or drive unit.

Some portions of the detailed description may be presented in terms ofalgorithms and symbolic representations of operations on data bitswithin a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of operations leading to adesired result. The operations are those requiring physicalmanipulations of physical quantities. Usually, though not necessarily,these quantities take the form of electrical or magnetic signals capableof being stored, transferred, combined, compared, and otherwisemanipulated. It has proven convenient at times, principally for reasonsof common usage, to refer to these signals as bits, values, elements,symbols, characters, terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, as apparent from the followingdiscussion, it is appreciated that throughout the description,discussions utilizing terms such as “processing” or “computing” or“calculating” or “determining” or “displaying” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the methods of some embodiments. The requiredstructure for a variety of these systems will appear from thedescription below. In addition, the techniques are not described withreference to any particular programming language, and variousembodiments may thus be implemented using a variety of programminglanguages.

In alternative embodiments, the machine operates as a standalone deviceor may be connected (e.g., networked) to other machines. In a networkeddeployment, the machine may operate in the capacity of a server or aclient machine in a client-server network environment or as a peermachine in a peer-to-peer (or distributed) network environment.

The machine may be a server computer, a client computer, a personalcomputer (PC), a tablet PC, a laptop computer, a set-top box (STB), apersonal digital assistant (PDA), a cellular telephone, an iPhone, aBlackberry, a processor, a telephone, a web appliance, a network router,switch or bridge, or any machine capable of executing a set ofinstructions (sequential or otherwise) that specify actions to be takenby that machine.

While the machine-readable medium or machine-readable storage medium isshown in an exemplary embodiment to be a single medium, the term“machine-readable medium” and “machine-readable storage medium” shouldbe taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“machine-readable medium” and “machine-readable storage medium” shallalso be taken to include any medium that is capable of storing, encodingor carrying a set of instructions for execution by the machine and thatcause the machine to perform any one or more of the methodologies of thepresently disclosed technique and innovation.

In general, the routines executed to implement the embodiments of thedisclosure, may be implemented as part of an operating system or aspecific application, component, program, object, module or sequence ofinstructions referred to as “computer programs.” The computer programstypically comprise one or more instructions set at various times invarious memory and storage devices in a computer, and that, when readand executed by one or more processing units or processors in acomputer, cause the computer to perform operations to execute elementsinvolving the various aspects of the disclosure.

Moreover, while embodiments have been described in the context of fullyfunctioning computers and computer systems, those skilled in the artwill appreciate that the various embodiments are capable of beingdistributed as a program product in a variety of forms, and that thedisclosure applies equally regardless of the particular type of machineor computer-readable media used to actually effect the distribution.

Further examples of machine-readable storage media, machine-readablemedia, or computer-readable (storage) media include but are not limitedto recordable type media such as volatile and non-volatile memorydevices, floppy and other removable disks, hard disk drives, opticaldisks (e.g., Compact Disk Read-Only Memory (CD ROMS), Digital VersatileDisks, (DVDs), etc.), among others, and transmission type media such asdigital and analog communication links.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof, means any connection or coupling,either direct or indirect, between two or more elements; the coupling ofconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, shall referto this application as a whole and not to any particular portions ofthis application. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively. The word “or,” in reference to alist of two or more items, covers all of the following interpretationsof the word: any of the items in the list, all of the items in the list,and any combination of the items in the list.

The above detailed description of embodiments of the disclosure is notintended to be exhaustive or to limit the teachings to the precise formdisclosed above. While specific embodiments of, and examples for, thedisclosure are described above for illustrative purposes, variousequivalent modifications are possible within the scope of thedisclosure, as those skilled in the relevant art will recognize. Forexample, while processes or blocks are presented in a given order,alternative embodiments may perform routines having steps, or employsystems having blocks, in a different order, and some processes orblocks may be deleted, moved, added, subdivided, combined, and/ormodified to provide alternative or subcombinations. Each of theseprocesses or blocks may be implemented in a variety of different ways.Also, while processes or blocks are, at times, shown as being performedin a series, these processes or blocks may instead be performed inparallel, or may be performed at different times. Further, any specificnumbers noted herein are only examples: alternative implementations mayemploy differing values or ranges.

The teachings of the disclosure provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the disclosure can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further embodiments of thedisclosure.

These and other changes can be made to the disclosure in light of theabove Detailed Description. While the above description describescertain embodiments of the disclosure, and describes the best modecontemplated, no matter how detailed the above appears in text, theteachings can be practiced in many ways. Details of the system may varyconsiderably in its implementation details, while still beingencompassed by the subject matter disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the disclosure should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the disclosure with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the disclosure to the specific embodimentsdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe disclosure encompasses not only the disclosed embodiments, but alsoall equivalent ways of practicing or implementing the disclosure underthe claims.

While certain aspects of the disclosure are presented below in certainclaim forms, the inventors contemplate the various aspects of thedisclosure in any number of claim forms. For example, while only oneaspect of the disclosure is recited as a means-plus-function claim under35 U.S.C. § 112(f), other aspects may likewise be embodied as ameans-plus-function claim, or in other forms, such as being embodied ina computer-readable medium. (Any claims intended to be treated under 35U.S.C. § 112(f) will begin with the words “means for”.) Accordingly, theapplicant reserves the right to add additional claims after filing theapplication to pursue such additional claim forms for other aspects ofthe disclosure.

The detailed description provided herein may be applied to othersystems, not necessarily only the system described above. The elementsand acts of the various examples described above can be combined toprovide further implementations of the invention. Some alternativeimplementations of the invention may include not only additionalelements to those implementations noted above, but also may includefewer elements. These and other changes can be made to the invention inlight of the above Detailed Description. While the above descriptiondefines certain examples of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its specific implementation, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention.

What is claimed is:
 1. A system for calibrating a radio frequency (RF)transceiver, the system comprising: a plurality of antennas including atest antenna element (AE); and a controller operatively coupled to thetest AE, wherein the controller is configured to: determine a phase atwhich a first RF signal was received by the test AE from at least onecalibration antenna; direct the test AE to transmit, at two or moredifferent sequential phase settings, a second RF signal to the at leastone calibration antenna; and identify, for subsequent use by one or moreof the plurality of antennas in transmitting an additional RF signaldirected to a location of an RF receiver device, a phase of the two ormore different sequential phase settings corresponding to a maximum peakpower that the second RF signal was received by the at least onecalibration antenna.
 2. The system of claim 1, wherein: the plurality ofantennas further includes a reference AE operatively coupled to thecontroller; and the controller is further configured to determine aphase at which the first RF signal was received by the reference AE fromthe at least one calibration antenna.
 3. The system of claim 2, whereinthe controller is further configured to direct the RF transceiver totransmit, to the at least one calibration antenna, data representativeof the determined phase at which the first RF signal was received by thereference AE from the at least one calibration antenna.
 4. The system ofclaim 2, wherein the controller is further configured to: compute areference phase by subtracting a reference path delay phase from thedetermined phase at which the first RF signal was received by thereference AE from the at least one calibration antenna; and direct thereference AE to continuously transmit a third RF signal at the referencephase to the at least one calibration antenna.
 5. The system of claim 1further comprising the at least one calibration antenna operativelycoupled to the controller.
 6. The system of claim 5, wherein theplurality of antennas include an antenna array operatively coupled tothe controller, and wherein the at least one calibration antenna isfurther positioned apart from, and in a near field with respect to, theantenna array.
 7. A method for calibrating a radio frequency (RF)transceiver having a plurality of antennas including a test antennaelement (AE), the method comprising: determining a phase at which afirst RF signal was received by the test AE from at least onecalibration antenna; directing the test AE to transmit, at two or moredifferent sequential phase settings, a second RF signal to the at leastone calibration antenna; and identifying, for subsequent use by one ormore of the plurality of antennas in transmitting an additional RFsignal directed to a location of an RF receiver device, a phase of thetwo or more different sequential phase settings corresponding to amaximum peak power that the second RF signal was received by the atleast one calibration antenna.
 8. The method of claim 7, wherein theplurality of antennas of the RF transceiver further includes a referenceAE, the method further comprising determining a phase at which the firstRF signal was received by the reference AE from the at least onecalibration antenna.
 9. The method of claim 8 further comprisingdirecting the RF transceiver to transmit, to the at least onecalibration antenna, data representative of the determined phase atwhich the first RF signal was received by the reference AE from the atleast one calibration antenna.
 10. The method of claim 8 furthercomprising directing the reference AE to continuously transmit a thirdRF signal at a reference phase to the at least one calibration antenna.11. The method of claim 10 further comprising computing the referencephase by subtracting a reference path delay phase from the determinedphase at which the first RF signal was received by the reference AE. 12.The method of claim 7 further comprising calculating a calibration valuefor the test AE according to a difference between the determined phaseat which the first RF signal was received by the test AE and theidentified phase of the two or more different sequential phase settingscorresponding to the maximum peak power.
 13. The method of claim 12further comprising adjusting, based on the calibration value, a phase ofthe test AE prior to the RF transceiver transmitting the additional RFsignal directed to the location of the RF receiver device.
 14. Themethod of claim 13, wherein adjusting the phase of the test AE comprisesadding the calibration value to the determined phase at which the firstRF signal was received by the test AE.
 15. The method of claim 7 furthercomprising receiving, from the at least one calibration antenna, datarepresentative of a received signal strength at which the second signalwas received by the at least one calibration antenna at each of the twoor more different sequential phase settings.
 16. The method of claim 15,wherein identifying the phase of the two or more different sequentialphase settings corresponding to a maximum peak power comprisesidentifying the phase according to the data representative of thereceived signal strength.
 17. The method of claim 7, wherein the test AEreceives the first RF signal from the at least one calibration antenna,and the second RF signal is transmitted at the sequential phase settingsfrom the test AE to the at least one calibration antenna along aplurality of paths, or reflected off one or more objects, in a multipathenvironment.
 18. The method of claim 7 further comprising: detecting asystem startup process of the RF transceiver; and performing thedetermining, directing and identifying steps in response to detectingthe system startup process.
 19. The method of claim 7 further comprisingiterating through the steps of the method for another test AE of theplurality of antennas of the RF transceiver.
 20. One or morenon-transitory computer readable media having program instructionsstored thereon which, when executed by at least one processor of a radiofrequency (RF) transceiver having a plurality of antennas including atest antenna element (AE), cause the RF transceiver to: determine aphase at which a first RF signal was received by the test AE from atleast one calibration antenna; direct the test AE to transmit, at two ormore different sequential phase settings, a second RF signal to the atleast one calibration antenna; and identify, for subsequent use by oneor more of the plurality of antennas in transmitting an additional RFsignal directed to a location of an RF receiver device, a phase of thetwo or more different sequential phase settings corresponding to amaximum peak power that the second RF signal was received by the atleast one calibration antenna.